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Australian agricultural biologists are currently researching weeping rice grass (Microlaena stipoides), a deep-rooted native relative of rice - VCE - SSCE Biology - Question 6 - 2007 - Paper 1
Question 6
Australian agricultural biologists are currently researching weeping rice grass (Microlaena stipoides), a deep-rooted native relative of rice. Their aim is to produc... show full transcript
Worked Solution & Example Answer:Australian agricultural biologists are currently researching weeping rice grass (Microlaena stipoides), a deep-rooted native relative of rice - VCE - SSCE Biology - Question 6 - 2007 - Paper 1
Step 1
The seed size trait is most likely to be polygenic. What is a polygenic trait?
Answer
A polygenic trait is a characteristic that is influenced by multiple genes. Rather than being determined by a single gene, polygenic traits result from the additive effects of several genes, each contributing to the overall phenotype. This can lead to a wide range of phenotypic variations in the trait.
Step 2
What might be the advantage of breeding this species for larger seed size?
Answer
Larger seeds in weeping rice grass might have several advantages. They often contain more stored nutrients, which can improve germination rates and seedling vigor. Additionally, larger seeds may provide better tolerance to environmental stresses, such as drought, by having more resources to draw on during early growth stages.
Step 3
If you were a farmer involved in a systematic breeding program, outline the steps you should take to develop a variety of weeping rice grass with large seeds.
Answer
- Selection of Parents: Begin by selecting parent plants with the largest seeds.
- Cross-Pollination: Cross-pollinate the selected plants to combine desirable traits.
- Seed Collection: Collect the seeds from the resulting plants and grow them out in controlled conditions.
- Evaluation: Assess the seed size of the offspring and select the largest for further breeding.
- Repeated Crosses: Repeat the process over several generations to reinforce the trait of larger seed size.
- Field Trials: Conduct field trials to evaluate the performance of the new variety in different conditions.
- Stabilization: Once desired traits are consistent, stabilize the variety and prepare for commercial production.